Selected Table of Contents
1. Age of Earth:
24, 271, 275, 334
2. Age of Solar System:
333, 334
3. Age of Universe:
332, 333
4. Big Bang:
350
5. Life:
3, 4, etc.
6. Biblical Themes:
270, 271, 275
7. Radiometric Dating:
24, 278, 311, 350, 469
8. Laws of Physics:
77
9. Geological Time Scale
313
10. Scientific
Research / Scientific Method 12-16
Chapter 1: Concepts & methods in Biology & Scientific Research / Scientific Method
pg3 ... What is life? ... To biologists ... the question opens up a story that has been unfolding in countless directions for several billion years! "Life" is an outcome of ancient events by which nonliving materials become assembled into the first living cells.
... all organisms are alike in key respects. ... they all grow and reproduce, based on instructions contained in their DNA.
... Millions of different organisms inhabit Earth, and many millions more lived and became extinct over the past 3.8 billion years.
... Theories of evolution, especially a theory of natural selection as first formulated by Charles Darwin, help explain the meaning of life’s diversity.
pg4 ... We and all other organisms are part of a journey that began almost 4 billion years ago, with the emergence of the first living cells.
p12 THE NATURE OF BIOLOGICAL
INQUIRY (SCIENTIFIC RESEARCH)
... consider approaching this or
any other collection of "facts" with a critical attitude. "Why should I
accept that they have merit?" The answer requires insight into how
biologists make inferences about
observations and then test the predictive power of their inferences against
actual experiences in nature or the laboratory.
Observations, Hypotheses,
and Tests:
To get a sense of "how to do science,"
start by following some practices that are pervasive in scientific
research:
1. Observe some aspect of nature, carefully check what others have found out about it, and then frame a question or identify a problem related to your observation.
2. Develop hypotheses, or educated guesses, about possible answers to questions or solutions to problems.
3. Using hypotheses as a guide, make a prediction - that is, a statement of what you shoulld observe in the natural world if you were to go looking for it. This is often called the "if-then" process.
4. Devise ways to test the accuracy of your predictions, as by making systematic observations, developing models, and conducting experiments.
5. If the tests do not turn out as you expected, check to see what might have gone wrong. ... maybe you overlooked a factor that influenced the test results. Or maybe the hypothesis is not a good one.
6. Repeat the tests or devise new ones - the more the better, for hypotheses thhat withstand many tests are likely to have a higher probability of being useful.
7. Objectively analyze and report the test results and the conclusions you have drawn from them.
You might hear someone refer to these practices as "the
scientific method," as if all scientists march to the drumbeat
of an absolute, fixed procedure. They do not. Many observe,
describe, and report on some subject, then leave it to others to hypothesize
about it. Some are lucky; they stumble unto information they are
not even looking for, although chance does favor the prepared mind.
It is not
one single method they have in common. It
is a critical attitude about being shown rather than told, and taking a
logical approach to problem solving.
Logic
encompasses thought patterns by which an individual draws a conclusion
that does not contradict the evidence used to support it. Lick a
lemon and you notice it's extremely sour. Lick ten more and you notice
the same thing each time, so you conclude all lemons are extremely sour.
You have correlated one specific (lemon) with another (sour). By
this pattern of thinking, called inductive
logic, an individual derives
a general statement from specific observations.
Express
the generalization in "if-then" terms, and you have a hypothesis:
"If you lick any lemon, then you will get an extremely sour taste in your
mouth." By this pattern of thinking, called deductive
logic, an individual makes inferences about specific consequences
or specific predictions that must follow from a hypothesis.
You decide to test the hypothesis by tracking down and sampling
all the varieties of lemons in the vicinity. One variety, the Meyer
lemon, is actually mellow, for a lemon. You also discover that some
people cannot taste anything. So you must modify
the original hypothesis: "If most people lick any lemon except
the Meyer lemon, they will get an extremely sour taste in their mouth."
Suppose, after sampling all the known lemon varieties in the world, you
conclude the modified hypothesis is a good one. You
can never prove it beyond all shadow of a doubt, because there might
be lemon trees growing in places people don't even know about. You
can say the hypothesis has a high probability of not being wrong.
Comprehensive observations
are a logical means to test the predictions that flow from hypotheses.
So are experiments.
These tests simplify observation in nature or the laboratory by manipulating
and controlling the conditions under which observations are made.
When suitably designed, observational
and experimental tests allow you to predict that something will happen
if a hypothesis isn't wrong (or won't happen if it is wrong).
For example, say you
decided to use Darwin's view of natural selection to explain wing patterns
of moths. By his reasoning, this trait or any other persists when
it improves odds for reproductive success. You
develop a hypothesis: Moth wing patterning is a visual signal
that helps males and females of a species identify each other and mate,
and thereby produce offspring.
Next,
you come up with a prediction based on it: Moths mate at night,
so if their wing pattern is a mating flag, then on moonless nights they
will not see the pattern and I won't see moths mating. You
test the prediction on a moonlit night, then on a moonless night.
Moths mate both times. Do your direct observations mean the hypothesis
is flawed? Maybe not; maybe your predictiion is flawed. What
if you overlooked a factor that affected the outcome? For example,
what if moths, like cats, see better than you do in the dark?
You devise an experimental
test to reveal whether wing pattern is not a mating flag. If moths
having an altered wing pattern still attracts mates, the prediction is
probably flawed. So you capture moths, paint an altered pattern on
their wings, and cage them with unaltered moths. You also set
up a control group.
p13 Control
groups are used to identify side effects during a test that involves
an experimental group. Ideally, a control group
is identical to an experimental group in all respects except for the variable
being studied.
Variables
are specific aspects of objects or events that may hiffer over time
and among individuals. Experimenters directly manipulate a single
variable that may support or disprove a prediction, and they also try to
hold constant any other variables that may influence the results.
In your case, a painted wing pattern is the key variable. But maybe
paint fumes, not the painted pattern, will be repulsive to potential mates.
Or maybe painting roughts up a moth in a way that will make it less attractive
than moths of the control group. (for instance, wing fluttering attracts
mates. What if the paint weighs enough to change the flutter frequency?)
To eliminate variables
that are unrelated to testing your predictiion, you paint moths of the
control group with the same paint and brushes, and handle them the same
way - but in their case you precisely duplicate the natural wing pattern.
The point of the manipulation is to make the experimental and control groups
identical except for the key variable. Now, if the moths having an
altered wing pattern still turn out to be lucky in love, then the experiment
will not support the prediction. ...
About
the Word "Theory"
Suppose no one has disproved a hypothesis after years
of rigorous tests. Suppose scientists use it to formulate more hypotheses
that successfully explain a broad range of phenomena. When a hypothesis
meets these criteria, it may become accepted as a scientific
theory.
You may hear someone apply the word "theory" to a
speculative idea, as in the expression "it's only a theory."
However, a scientific
theory differs from speculation for a simple reason: Many
researchers have tested its predictive power many times, in many different
ways, and have found no evidence to disprove it. That is why
Darwin's view of natural selection is a highly regarded theory. Biologists
use it successfully to explain such diverse issues as the origin of life,
the relationship between plant toxins and plant-eating animals, the sexual
advantages of brightly colored or patterned wings or feathers, the reason
why certain cancers run in families, or why antibiotics that doctors often
prescribe are no longer effective. By giving reasoned evidence that
evolution occurred in the past, the theory even influenced views of Earth
history.
An exhaustively tested
theory might be as close to the truth as scientists can get with the evidence
at hand. For example, Darwin's theory stands, with only minor modification,
after more than a century of thousands of different tests. As biologists
realize, we cannot show the theory holds under all possible conditioins;
an infinite number of tests would be required to do so. As for any
theory, we can only say it has a high or low probability of being a good
one. So far, (1998)
biologists haven't found any evidence that calls Darwin's theory into question.
Yet they still keep their eyes open for new informatiion and new ways of
testing that might disprove its premises.
And this point get
us back to the value of thinking critically.
Scientists must keep asking themselves: Will observatioins or experiments
show that a hypothesis is false? They expect one another to put aside
pride or bias by testing ideas, even in ways that may prove them wrong.
Even if an individual doesn't or won't do this, others will - for science
proceeds as a community that is both cooperative and competitive.
Ideally, its practitioners share their ideas, with the understanding that
it is just as important to expose errors as it is to applaud insights.
Individuals can and often do change their minds when presented with contradictory
evidence. As you will see, this is a strength of science, not a weakness.
A scientific
approach to studying nature is based on asking questions,
formulating hypotheses, making predictions, devising tests, and objectively
reporting the results.
A scientific
theory is a testable explanation about the cause or causes
of a broad range of related phenomena. It remains open to tests,
revision, and tentative acceptance or rejection.
THE POWER AND PITFALLS OF EXPERIMENTAL TESTS (Focus on Science)
pg14 An Assumption of Cause and Effect: Experiments start from a premise that any aspect of the natural world has one or more underlying causes, whether hidden or not. With this premise, science is distinct from faith in the supernatural (meaning "beyond nature"). Experiments must deal with potentially falsifiable hypotheses. Such hypotheses can be tested in the natural world in ways that might disprove them.
Experimental Design: To get conclusive test results, experimenters rely on certain practices. They refine a test design by searching the literature for related information. They design their own experiments to test one prediction of a hypothesis at a time. Each time, they set up a control group as a standard for comparison with one or more experimental groups.
p15 Identifying Important Variables: In nature, many factors can influence the outcome (of an experiment) ... That is why researchers try to simplify and control the variables in their experiments. Variables, recall, are specific aspects of objects or events that may differ over time and among individuals.
Sampling Error: ... experimenters generally use samples (or subsets) of populations, events, and other aspects of nature. If they don't use large-enough samples, they run the risk of performing tests with groups that are not representative of the whole. In general, the larger the sample, the less likely it will be that differences among individuals will distort the results.
Bias In Reporting The Results: Whether intentional or not, experimenters run the risk of interpreting data in terms of what they want to prove or dismiss. A few have even been known to fake measurements or nudge findings in ways that reinforce their own bias. That is why science emphasizes presenting test results in quantitative terms - that is, with actual counts or some other precise form. Doing so allows other experimenters to check or test the results readily and systematically, ...
p16
THE LIMITS OF SCIENCE
The call for objective testing strengthens
the theories that emerge from scientific studies. It also puts
limits on the kinds of studies that can be carried out.
Beyond the realm of science, some events remain
unexplained. Why do we exist, for what
purpose? Why does any one of us have to die at a particular moment?
Such questions lead to subjective
answers, which come from within, as an outcome of all the experiences
and mental connections shaping our consciousness.
Because people differ vastly in this regard,
subjective answers do not readily lend themselves to scientific analysis
and experiments.
This is not to say subjective answers are without value. No human
society can function for long unless its members share a commitment to
certain standards for making judgments, even subjective ones. The
moral, aesthetic, philosophical, and economic standards vary from one society
to the next. But they all guide their members in deciding what is
important and good, and what is not. All attempt to give meaning
to what we do.
Every so often, scientists stir up controversy when they happen to explain
some part of the world that was considered to be beyond
natural explanation - that is, as belonging to the "supernatural."
This is often true when a society's moral codes have become interwoven
with religious narratives.
Exploring some longstanding view of the world from a scientific perspective
may be misinterpreted as questioning morality, even though the two are
not the same thing.
For example, centuries ago in Europe, Nicolaus Copernicus
studied the planets and concluded the Earth circles the sun.
Today this seems obvious enough. Back then it was heresy. The
prevailing belief was that the Creator made the Earth (and, by extension,
humankind) the immovable center of the universe.
Later a respected scholar, Galileo Galilei, studied
the Copernican model of the solar system, thought it was a good one, and
said so. He was forced to retract his statement publicly, on his
knees, and put the Earth back as the fixed center of things. (Word has
it that when he stood up he muttered, "Even so, it does move.")
Later still, Darwin's
theory of evolution ran up against
the same prevailing belief.
Today, as then, society has sets of standards. Those standards might
be questioned when a new, natural explanation runs
counter to supernatural beliefs. This doesn't
mean that the scientists who raise questions are less
moral, less lawful, less sensitive, or less caring than anyone else.
It simply means one more standard guides their
work: The
external world, not internal conviction, must be the testing ground for
scientific beliefs.
Systematic observations, hypotheses, predictions, tests - in all these
ways, science
differs from systems of belief that are based on faith, force, or simple
consensus.
Summary
4. The diversity among organisms has
arisen through mutations,
which are changes in the structure of DNA molecules. The changes are the
foundation for variation in heritable traits. ...
5. Darwin’s theory of evolution by natural selection is a cornerstone of biological inquiry. Its key premises are:
a. Individuals of a given population differ in their versions of the same heritable trait. Variant forms of traits may affect the ability to survive and reproduce.
b. Natural selection is the outcome of differences in survival and reproduction among individuals that show variation in one or more traits. Adaptive forms of a given trait tend to become more common; less adaptive ones become less common or disappear. Thus the traits we use to define a population can change over time; the population can evolve.
6. There are many diverse methods of scientific inquiry. The following terms are important to all of them:
a. Theory: An explanation of a broad range of related phenomena, supported by many tests.
b. Hypothesis: A possible explanation of a specific phenomenon. Sometimes called an educated guess.
c. Prediction: A claim about what can be expected in nature, based on the premises of a theory or hypothesis.
d. Test: An attempt to produce actual observations that match predicted or expected observations.
e. Conclusion: A statement about whether a theory or hypothesis should be accepted, modified, or rejected, based on tests of the predictions derived from it.
7. Systematic observations, hypotheses, predictions, and relentless tests are the foundation of scientific theories. The external world, rather than internal conviction, is the testing ground for those theories.
p21 Key Concepts: 6. Life originated in water ...
p24 Using Radioisotopes to Date the Past ... Some time ago, geologists hypothesized that if newly formed rocks slowly accumulate on top of older rocks, then fossils in older rock layers must be more ancient than those in more recently deposited ones. They used this perception to count backward through great numbers of rock layers and thereby construct a chronology of Earth history - a geologic time scale. ... theyy used sequences of fossils and other clues in the rocks to define the boundaries of the time scale’s successive spans. However, no one was able to assign firm dates along the length of the scale until the discovery of radioactive decay, which made it possible to convert the relative ages into absolute ones.
By a method called radiometric dating, researchers now measure the proportions of (1) a radioisotope in a mineral that became trapped long ago in a brand-new rock and (2) a daughter isotope that formed from it in the same rock ...
... Half-life is the time it takes for half of a given quantity of any radioisotope to decay into a different, less unstable daughter isotope. The rate of decay is constant; changes in pressure, temperature, or chemical state cannot alter it.
... By using uranium (238), with its half-life of 4.5 billion years, researchers realized the Earth formed more than 4.6 billion years ago.
... Radiometric dating works for volcanic rocks or ashes. However, most fossil-containing rocks formed by the compaction of sand and other sediments. Thus the only way to date most fossil-containing rocks is to determine their position relative to volcanic rocks in the same area.
pg52 ... The nucleic acids DNA and RNA, built of nucleotides, are the basis of inheritance and reproduction.
pg 77 ... 1. Three generalizations constitute the cell theory:
a. All living things are composed of one or more cells.
b. The cell is the smallest entity that retains the properties of life. ...
c. New cells arise only from cells that already exist.
pg110 ... Summary:
2. Two laws of thermodynamics affect life.
First, energy undergoes conversion from one form to another, but its total amount never increases or decreases as a result of any conversion. Thus the total amount of energy in the universe holds constant.
Second,energy spontaneously flows in one direction, from forms of higher to lower quality.
4. The sun is life’s primary energy source.
pg149 ... Parent cells must provide their daughter cells with hereditary instructions, encoded in DNA, and enough metabolic machinery to start up their own operation.
pg189 ... Summary 1. A gene is a unit of information about a heritable trait. ...
pg214 ... Summary 1. Genes, the units of instruction for heritable traits, are arranged one after the other along chromosomes.
p217 ... In all living cells, DNA molecules are the storehouses of information about heritable traits.
Chapter 14 ... Key Concepts ...
5. With few exceptions, the genetic "code words" by which DNA instructions are translated into proteins are the same in all species of organisms.
6. A mutation is a permanent change in a gene’s base sequence. Such changes are the original source of genetic variation in populations.
7. Mutations give rise to alterations in protein structure, protein function, or both. The alterations may lead to small or large differences in traits among the individuals of a population.
pg267 ... Uncountable gene mutations and other forms of genetic "experiments" have been proceeding in nature for at least 3 billion years.
pg 270 Chapter 17 - Emergence of Evolutionary Thought
... we turn to evolutionary theories and to the ways in which they can be used to interpret the past and present, even to predict possible futures for the natural world. Today the theories are routinely used to guide scientific investigations in many fields, and they are widely accepted in society at large.
... early evolutionists ... astounding theories, which opened a window on the interrelatedness of the geologic record, the fossil record, and the existing sweep of biological diversity.
... Others were unable to reconcile them with THE Bible,the premier book of the Western world. For generation after generation, that book had been helping people come with the uncertainties of life, death, and unpredictable forces of nature. Presumably eyewitness accounts of volcanism, great floods, and other catastrophes were interwoven into its narrative. Modern scientists have indeed found physical evidence of many ancient catastrophic events, so we know bad things did happen. However, those accounts had been assigned meaning through the prism of prevailing cultural beliefs and a limited understanding of geologic processes.
For example, the Jordan Valley is a long depression in the Earth’s crust, between the Red Sea to the south and the Dead Sea to the north. About 4,000 years ago, the notorious cities of Sodom and Gomorrah apparently flourished in this valley, at the south end of the Dead Sea. By biblical account, "brimstone and fire rained upon the cities ... and the smoke of the land went up like the smoke of a furnace." Both cities were destroyed, and stories of the horrified survivors found their way into the Biblical narrative.
p271 Scientists now have satellite images of the straight walls of the valleys. They see physical evidence of hot springs past and present, great lava flows, and violent tremors - all signs of deep cracks (faults) in the Earth’s crust. Severe earthquakes must have tilted a portion of the crust along the fault at the southern end of the Dead Sea. As the ground heaved, lava poured from the depths, hot springs spewed forth a sulfurous brew, and the violently displaced waters of the sea undoubtedly flooded cities along its shores.
As another example, during the heydey of ancient Egyptian civilization some 3,500 years ago, a volcanic island near Greece blew apart and generated seismic sea waves that may have been 100 meters high. Twenty minutes later, the giant waves slammed into the island of Crete to the south. Apparently the abrupt collapse of the Minoan civilization coincided with this catastrophe; the Minoan capital on Crete is thought to have been leveled at the same time as the eruption. Those who survived the deluge would have been further terrified, for the skies must have been darkened for days as prevailing winds blew volcanic ash across the island. This account comes from modern-day studies of Thera, a small, crescent-shaped island between Greece and Crete. The island is merely the exposed uppermost part of a great submerged crater, 400 meters deep.
Quite possibly, that violent episode in Earth history was transformed into thebiblical account of a Great Deluge. If, as European scholars believed, the very first humans were expelled from paradise as punishment for their sins, and if their descendants had continued to indulge in sinful ways, then the Great Deluge must have been divinely invoked to punish their offspring, too. Those scholars also believed that the Earth was only about 6,000 years old.
If so many catastrophes had been inflicted on humans in so short a time, then all changes to the Earth’s surface must have occurred by sudden, violent geologic processes. These were the core hypotheses of what came to be known as the theories of catastrophism.
Biological science emerged within the framework of such prevailing beliefs, and so did awareness of change in the Earth and its creatures. Understand this fact, and you will gain insight into why acceptance of the very idea of biological evolution was so long in coming.
pg 271 Key Concepts:
1. ... Evolutionary theories gave early scholars a new way of interpreting and investigating the natural world.
2. Today we define biological evolution as heritable changes in lineages, or lines of descent. Evidence of evolution comes from investigations that began nearly two centuries ago.
3. ... geologist found evidence of the evolution of life in fossil sequences, as recorded in the cakelike layers of sedimentary rock.
4. As Charles Darwin & Alfred Wallace perceived, evolution can occur by way of natural selection.
5. ... key premises of the theory (of evolution)
Populations of each species are characterized by the heritable traits that its individuals share. Those traits vary in their details from one individual to the next. Over time, the forms of traits that prove to be most adaptive in a given environment increase in a population, and other forms do not. Thus the traits that characterize a population can change over time; the population can evolve.
p275 ... the theory of uniformity. It challenged the prevailing views of the age of the Earth. The theory bothered (BIBLICAL) scholars who firmly believed the Earth was less than 6,000 years old. They thought people had recorded everything that happened during those thousands of years, and in all that time no one ever mentioned seeing a species evolve. Yet by Lyell’s calculations, it must have taken millions of years to mold the present landscape. Wasn’t that enough time for species to evolve in diverse ways? Later, Darwin thought so.
Prevailing beliefs can influence how we interpret clues to natural processes and their observable outcomes. ...
pg278 Regarding The First of the "Missing Links" ... where were the "missing links"? That is, if each species evolved from others, then where were the fossils of all the transitional forms? Where were the species with traits that bridged two major groups of organisms?
More than a century would pass before more fossil finds as well as the application of molecular biology and genetic analysis would yield plausible answers to that question. In Darwin’s time, though, the presumed absence of transitional forms was a major point of contention in discussions of the theory.
... a fossil of just such a transitional form ... unearthed at the Solnhofen limestones of Bavaria, in southern Germany. ... named Archaeopteryx (meaning "ancient winged one").
Between 1860 and 1988 six specimens of Archaeopteryx and a fossilized feather were found. ... microscopic examination confirmed that the fossils are real. ... Through radiometric dating methods, we now know that Archaeopteryx lived 150 million years ago.
pg279 ... Natural selection results in modifications of traits within a line of descent. Over time, it may bring about the evolution of a new species, with an array of traits that is uniquely its own relative to other species.
One "test" of Darwin’s theory would be evidence of one major kind of organism changing into another kind. Archaeopteryx, an extinct, transitional form between reptiles and birds, provided early evidence. Not until many decades later did studies at many levels of biological organization offer a large body of evidence in support of his theory of evolution by natural selection.
Chapter 18 Microevolution
pg 281 ... evolution simply means genetic change through time.
Key Concepts: ...
2. In the population as a whole, each gene may exist in two or more slightly different molecular forms, called alleles. Individuals may or may not inherit the same combinations of alleles, so they may not be exactly alike in the details of their traits.
3. ... Microevolution means that changes have occurred in a population’s allele frequencies over time.
4. Allele frequencies can change through mutation, gene flow, genetic drift, and natural selection. Mutation alone produces new alleles. Gene flow, genetic drift, and natural selection shuffle existing alleles into, through, or out of populations.
5. Natural selection is not an "agent", something that is purposefully searching for the "best" individuals in a population. Natural selection simply is the difference in survival and reproduction among individuals that differ in one or more traits. The difference, however, leads to a continuing adaptation of a species to its environment.
pg 286 Directional Selection ... allele frequencies that are responsible for a range of phenotypic variation shift in a consistent direction ... The case of the Peppered Moths ... Pesticide Resistance ... Antibiotic Resistance ...
pg308 Summary ...
1. A species is a single kind of organism, recognized partly in terms of its morphology.
2. By the biological species concept, a
species consists of one or more populations of individuals that are, under
natural conditions, interbreeding and producing fertile offspring, and
that are reproductively isolated from other such populations. The concept
identifies a species mainly in terms of the portion of alleles that promote
or maintain reproductive isolation. It applies only to sexually reproducing
organisms.
Chapter 20 The Macroevolutionary Puzzle
pg310 ... fossils have been analyzed in increasingly refined ways. Together with biochemical studies and other modern sources of information, they yield good evidence of evolution through vast spans of time.
pg311 ... all species that have ever evolved are related to one another, by way of descent. This principle of evolution guides efforts to make sense of scattered and often puzzling scraps of evidence of past life. It guides the task of identifying and sorting out the many lines of descent, or lineages, that connect all species, past and present.
Ultimately, then, life is a story of species - of how and when each originated, whether its defining traits persisted or were modified, and whether it vanished or endured.
Life also is a story of macroevolution - of large-scale patterns, trends, and rates of change among families and other more inclusive groups of species.
pg311 Key Concepts:
1. In the evolutionary view, all species that have ever lived are related, some closely, others remotely so. This relatedness exists because each new species had to evolve from variant individuals of species that already existed, starting with the first living cells to appear on earth.
2. The term macroevolution refers to the patterns, trends, and rates of change among lineages over geologic time.
3. The fossil record, the geologic record, and radiometric datingof rocks yield evidence of macroevolution.
4. Anatomical comparisons between major lineages help us understand and reconstruct patterns of change through time. Among the most revealing aspects of anatomy are homologous structures in the embryos or adult forms of different lineages. They signify descent from a common ancestor.
5. Biochemical comparisons within and between major lineages also provide evidence of macroevolution.
p313 ... Fossils, the stone-hard physical evidence of ancient life, are present in layers of sedimentary rock. The deeper the layers, the older the fossils. The geologic time scale is based on sequences of fossils in sedimentary rocks.
pg313 Geologic Time Scale:
ERA PERIOD EPOCH (million years ago)
Cenozoic
Quaternary Recent
0 -.01
Pleistocene
.01 - 1.55
Tertiary
Pliocene
1.55 - 5
Miocene
5 - 25
Oligocene
25 - 38
Eocene
38 - 54
Paleocene
54 - 65
Mesozoic
Cretaceous Late
65 - 100
Early
100 - 138
Jurassic
138 - 205
Triassic
205 - 240
Paleozoic
Permian
240 - 290
Carboniferous
290 - 360
Devonian
360 - 410
Silurian
410 - 435
Ordovician
435 - 505
Cambrian
505 - 550
Proterozoic Eon
550 - 2500
Archean Eon & Earlier
2500 - 4600
p314 ... the Grand Canyon of the American Southwest, once part of an ocean basin. Its layers of sedimentary rock formed gradually over hundreds of millions of years. Geologic forces lifted them above sea level. Later, the erosive force of rivers carved the deep canyon walls and so exposed the ancient stacked layers.
p315 ... Over the past 3.8 billion years, changes in the Earth’s crust, the atmosphere, and the oceans profoundly affected the evolution of life. Certain boundaries of the geologic time scale mark abrupt transitions in the evolutionary story.
pg316 Evidence from Comparative Embryology:
Strong evidence of evolution comes from anatomical comparisons of major lineages. This field of inquiry is called comparative morphology.
pg317 ... From comparative embryology, some evidence of evolutionary relationship among vertebrates. (a) Adult vertebrates show great diversity, yet the very early embryos retain striking similarities. This is evidence of change in a common program of development. (b) Fishlike structures still form in early embryos of reptiles, birds, and mammals ...
... The early embryos of vertebrates strongly resemble one another because they have inherited the same ancient plan for development.
pg321 ... Biochemical similarities are greatest among the most closely related species and weakest among the most distantly related ...
p325 ... Reconstructing the evolutionary history of a given lineage must be based on detailed understanding of the morphology, life-styles, and habitats of the groups represented, and on biochemical comparisons of its existing members.
pg329 SUMMARY (of chapter 20 - The Macroevolutionary Puzzle)
1. There is an underlying continuity of relationship among all species, past and present. The patterns, trends, and rates of change among groups of species over long spans of time are called macroevolution.
2. The fossil record, the geologic record, comparative morphology, and comparative biochemistry all yield extensive evidence of evolution. The evidence is based on similarities and differences in body form, functions, behavior, and biochemistry.
3. The completeness of the fossil record is variable in terms of the species represented, where they lived, and the stability of their tombs since fossilization occurred.
a. Fossilization starts when an organism or traces of it are buried in volcanic ash or in sediments. Dissolved inorganic compounds infuse the remains. Sediments gradually accumulate above them, and pressure and chemical changes transform the remains to stone.
b. Just as life evolved irreversibly from the first cells, so has the Earth evolved in irreversible ways.
c. By the plate tectonics theory, the Earth’s crust is fractured into thin plates, like a cracked eggshell, and the movements of these plates slowly raft continents to new positions. Ocean and atmospheric currents shift accordingly. The fossil record and geologic record show that such changes have influenced life’s evolution.
4. Comparative morphology has revealed similarities in embryonic development that indicate evolutionary relationship among major groups. It also has identified homologous structures;, which are shared as a result of descent from a common ancestor, among groups.
5. Comparative biochemistry identifies
similarities and differences among species at the molecular level. All
species have an accumulation of neutral mutations in highly conserved genes.
Such mutations are like ticks of a molecular clock; they help date
divergences from a common ancestor. Other comparisons use nucleic acid
hybridization, gene sequencing, and other methods to discern relative evolutionary
distances among species.
pg332 THE ORIGIN AND EVOLUTION OF LIFE - In The Beginning
... the long wavelengths that originated from faraway galaxies many billions of years ago are only now reaching the Earth. By every known measure, all the near and distant galaxies suspended in the vast space of the universe are moving away from one another, which means that the universe is expanding. And the prevailing view of how the colossal expansion came about accounts for every bit of matter in the universe, in every living thing.
p333 ... 12 to 15 billion years (ago) ... all galaxies, all matter, and all of space are compressed into a hot, dense volume about the size of the sun. You have arrived at time zero. That incredibly hot, dense state lasted only for an instant. What happened next is known as the BIG BANG, a stupendous, nearly instantaneous distribution of all matter and energy everywhere, through all of the known universe. About a minute later, temperatures dropped to a billion degrees. Fusion reactions produced most of the light elements, including helium, which are still the most abundant elements throughout the universe.
Radio telescopes have detected relics of the big bang in the form of cooled and diluted background radiation, left over from the beginning of time.
Over the next billion years, stars started forming as gaseous material contracted in response to the force of gravity. When stars become massive enough, nuclear reactions were ignited in their central region, and they gave off tremendous light and heat. As the massive stars continued to contract, many became dense enough to promote the formation of heavier elements.
All stars have a life history, from birth to an often spectacularly explosive death. In what might be called the original stardust memories, the heavier elements released during the explosions became swept up during the gravitational contraction of new stars, and they became raw materials for the formation of even heavier elements. ... the Hubble space telescope is providing astounding glimpses of star-forming activity, as in the dust clouds of Orion, Serpens, and other constellations.
Now IMAGINEa time long ago, when explosions of dying stars ripped through our galaxy and left behind a dense cloud of dust and gas that extended trillions of kilometers in space. As the cloud cooled, countless bits of matter gravitated toward one another. By 4.6 billion years ago, the cloud had flattened out into a slowly rotating disk. At the dense, hot center of that disk, the shining star of our solar system - the sun - was born.
... a principle that can help us organize separate bits of information about the past: Life is a magnificent continuation of the physical and chemical evolution of the universe, of galaxies and stars, and of the planet Earth.
pg333 KEY CONCEPTS
1. A great body of evidence suggeststhat life originated more than 3.8 billion years ago. Its origin and subsequent evolution have been linked to the physical and chemical evolution of the universe, the stars, and the planet Earth.
2. All of the inorganic and organic compounds necessary for self-replication, membrane assembly, and metabolism ... for the structure and functioning of living cells ... could have formed spontaneously under conditions that existed on the early Earth.
3. The history of life, from its chemical beginnings to the present, spans five intervals of geologic time ...
7. Throughout the history of life, asteroid impacts, drifting and colliding continents, and other environmental insults have had profound impact on the direction of evolution.
pg 334 ORIGIN OF THE EARTH:
Cloudlike regions of the universe ... are mostly hydrogen gas. These clouds also contain water, iron, silicates, hydrogen cyanide, ammonia, methane, formaldehyde, and some other simple organic and inorganic substances.
The contracting cloud from which our solar system evolved probably was similar in composition. Between 4.6 and 4.5 billion years age, the periphery of the cloud cooled. Mineral grains and ice orbiting the sun started to clump together as a result of electrostatic attraction and the pull of gravity. In time, larger, faster clumps started colliding and shattering. Some became more massive by sweeping up asteroids, meteorites, and the other rocky remnants of collisions, and gradually they evolved into planets.
... Four billion years ago, the Earth was a thin-crusted inferno. In less than 200 million years, life had originated on its surface. We have no record of the event.
p335 ... Many diverse experiments yield indirect evidence that the complex organic molecules characteristic of life could have formed under conditions that existed on the early earth. ... Stanly Miller conducted the first experimental test of that prediction. First he mixed methane, hydrogen, ammonia, and water inside a reaction chamber ... Then he kept the mixture circulating and bombarded it with a spark discharge to simulate lightning. In less than a week, amino acids and other small organic compounds had formed.
p339 ... The first cells evolved by about 3.8 billion years ago ...
p340 ... One fossil treasure is a strand of bacterial cells that lived 3.5 billion years ago, not long after the time that life originated.
p344 ... We divide the Mesozoic into the Triassic, Jurassic, and Cretaceous periods. It lasted about 175 million years. Early on in the Cretaceous, the supercontinent Pangea started to break up. Its huge fragments slowly drifted apart, and we can assume that the resulting geographic isolation favored divergences and speciation.
... Early in the Triassic, the first dinosaurs evolved from a reptilian lineage.
p345 ... The Mesozoic was a time of major adaptive radiations and of a mass extinction in which the last dinosaurs and many marine organisms disappeared.
p346 ... It has only been about 50,000 years since the first fully modern humans walked the Earth. ... the dinosaurs ... their lineage dominated the land for 140 million years. In the end, did it matter? Not a bit. Sixty-five million years ago, at the Cretaceous-Tertiary (K-T) boundary, nearly all remaining members of their most excellent lineage perished. Why?Bad luck.
p349 ... 1.65 mya (million years ago) to present. ... Modern humans evolve ...
... 65 mya. Apparent asteroid impact causes mass extinction of all dinosaurs ...
... 135-65 mya. Pangea (single world landmass) breakup ...
... 4,6000-3,800 mya. Formation of Earth’s crust, first atmosphere, and seas. Chemical, molecular evolution leading to origin of life ...
p350 SUMMARY
1. The story of life begins with the "BIG BANG", a model of the origin of the universe
a. By this model, all matter and all of space were once compressed in a fleeting state of enormous heat and density. Time began with the near-instantaneous distribution of all matter and energy throughout the known universe, which has been expanding since.
b. Nearly all helium and other light elements, the most abundant elements of the universe, formed right after the big bang. Heavier elements originated during the formation, evolution, and death of stars.
c. Every element of the solar system, the Earth, and life itself is a product of the physical and chemical evolution of the universe and its stars.
d. Four billion years ago, the Earth had a high-density core ...
5. Life originated by 3.8 billion years ago. ...
6. Abrupt discontinuities in the fossil record mark the times of global mass extinctions. We use them as boundary markers for five great intervals in a geologic time scale. Radiometric Dating has allowed us to assign absolute dates to this time scale:
a. Archean: 3.9 billion to 2.5 billion years ago
b. Proterozoic: 2.5 billion to 550 million years ago
c. Paleozoin: 550 to 240 million years ago
d. Mesozoic: 240 to 65 million years ago
e. Cenozoic: 65 million years ago to the present
p368 ...1. A major divergence occurred soon after the origin of life. One lineage gave rise to the eubacteria, and the other to the common ancestors of archaebacteria and eukaryotic cells. ...
p370 More than 2 billion years ago ... Ever since the time of life’s origin, the Earth’s atmosphere had been free of oxygen, and anaerobic bacteria had reigned supreme. ... An oxygen-producing pathway of photosynthesis had been operating in vast populations of cells. Gaseous oxygen had been dissolving in aquatic habitats and escaping into the air, and its atmospheric concentration was beginning to approach its current level. ... a short evolutionary step from having a capacity to neutralize oxygen to using it in metabolic reactions ...
p414 ... Plants invaded the land more than 430 million years ago. ...
p416 ... In August of 1994, about 900 million years after the first animals appeared on Earth, Madeleine made her entrance (a modern day child was born). ... and ifwe are interpreting the fossil record correctly, then five million years ago the offspring of individuals on the road to modern humans resembled her in some respects but not others. Sixty million years ago, the primate ancestors of those individuals were giving birth precariously, up in the trees. Two hundred and fifty million years ago, mammalian ancestors of those primates were giving birth - and so on back in time to the very first animals, ... Cambrian animals ... one bunch flourished 530 million years ago, ...
p417 ... Animals reproduce sexually and often asexually, and their embryos develop in a series of continuous stages.
p446 ... platypus, a web-footed mammal about the size of a housecat ... Like the other mammals, the duck-billed platypus (Ornithorhynchus anatinus) has mammary glands and hair. And yet, like birds and reptiles, it has a cloaca, a single enlarged duct through which gametes, feces, and excretions from the kidneys pass. It lays shelled eggs, as birds and most reptiles do. Its young hatch pink and unfinished ... Its flesh bill does look ducklike, and it broad, flat, furry tail does look like the one on a beaver ...
... With its unusual traits, the platypus
invites us to challenge preconceived notions of what constitutes "an animal"
...
p469 Chapter 29 HUMAN EVOLUTION
... a cave near Lascaux ... France ... Magnificent sketches, engravings, and paintings ... Radiometric dating revealed that they were 17,000 to 20,000 years old. The prehistoric artists ... they captured ... bison, stags, stallions, ibexes, lions, a rhinoceros, and a heifer ...
... Even earlier, art was committed to the walls of caves throughout southern France, northern Spain, and Africa, as when people made more than 150 imprints and outlines of hands in the cave of Gargas, in the Pyrenees, some 25,000 years ago.
Who were these artists? From their fossilized remains, we know they were people anatomically like us. From the way they planned and executed their art, we sense a level of abstract thinking that is unique to humans.
The quality of "humanness" did not emerge
out of thin air. If we could go back 5 million years in time, to
the place where the most recent ancestors of humans apparently originated,
we might find ourselves in Africa ... back an additional 55 million years,
to ancient tropical forests in which primates originated ... The mammalian
ancestors of the primates evolved 250 million years ago, vertebrate ancestors
of mammals evolved long before that, ancestors of vertebrates and all other
animal groups evolved 900 million years ago - and so on back to the origin
of the first living cells.
... keep this greater evolutionary
story
in mind. Our "uniquely" human traits emerged through modification of traits
that evolved earlier, in ancestral forms.
p469 KEY CONCEPTS
1. In the primate branch of the mammalian lineage are the prosimians, tarsioids, and antropoids (monkeys, apes, and humans). Apes and humans are hominoids. Only humans and some extinct species with a mosaic of apelike and humanlike traits are further classified as hominids. ...
5. ... Eventually, the evolution of the brain became interlocked with cultural evolution.
6. Unlike earlier hominids, Homo erectus and H. sapiens displayed remarkable behavioral flexibility and creative experimentation with their environment, as when they started using fire. This characteristic allowed them to survive the challenges of dispersing into novel and often harsh environment around the world.
p474 ... Between 2.5 and 1.6 million years ago, one or two forms of H. habilis (Homo habilis - meaning "handy man") lived in ... Africa ...
Fossil hunters have found numerous stone tools that date to the time of H. habilis. But they cannot say with certainty that H. habilis was the only species that made them. Possibly australopiths as well as H. habilis used sticks and other perishable tools before then, as modern apes do, but we have no way of knowing. Maybe ... Maybe ...
... Paleoanthropologist Mary Leakey was the first to discover evidence of toolmaking at Africa’s Olduvai Gorge ... the stone tools of H. habilis did not change much for the next 500,000 years.
pg475 The ancestors of modern humans apparently stayed put in Africa until about 2 million years ago. At that time, genetic divergence from early members of Homo led to Homo erectus, a human species that the fossil record places on the evolutionary road to modern humans. ... name means "upright man" ... its populations walked out of Africa, turned left into Europe, and right into Asia. ... H. erectus fossils from Southeast Asia and the former Soviet republic of Georgia are 1.8 million and 1.6 million years old.
... Remains of fire use date from an ice age in the early Pleistocene. ...
... Judging from fossils in Africa, Homo sapiens had evolved by 100,000 years ago. The origin and radiations of early H. sapiens are hotly debated topics. ...
... One group of early humans, the Neanderthals,
lived in Europe and the Near East from 200,000 to 35,000 years ago.
... Their disappearance coincided with the appearance of anatomically modern
humans in the same regions 40,000 to 30,000 years ago. ... we don’t know
yet what happened to them.
From 40,000 years ago to today, human
evolution has been almost entirely cultural, not biological
-- and so we leave tthe storywith
these conclusions: Humans spread rapidly through the world by devising
cultural means to deal with a broad range of environments. ... they developed
rich and varied cultures. Even though hunters and gatherers persist in
parts of the world, others moved from "stone-age" technology to the age
of "high tech," attesting to the great plasticity and depth of human adaptations.
p476 IF researchers are interpreting the fossil record of human evolution correctly, then it would seem that Africa was the cradle for us all. ... no one has found any fossils of humans that are older than 1 million years except in Africa. H. erectus coexisted for a time with earlier humans (H. habilis) before dispersing from the African savannas to the cooler grasslands, forests, and mountains of Europe and Asia. They apparentlyleft Africa in waves between about 2 million and 500,000 years ago. ...
AFRICAN EMERGENCE MODEL ... holds that H. sapiens --modern humans-- originated in sub-Saharan Africa somewhere between 200,000 and 100,000 years ago. Only later did H. sapiens populations move out of Africa, then into other regions ...
SUMMARY (chap 28): ...
3. The first primates were small, rodentlike mammals that evolved by 60 million years ago in tropical forests. ... some lineages gave rise to anthropoids, including the ancestors of monkeys, apes, and humans, by 35 million years ago.
4. Apelike forms (the first hominoids) evolved between 25 and 13 million years ago, in the Miocene. In Africa, some had given rise to australopiths, the earliest known hominids, before 4 million years ago. ...
5. H. habilis, the earliest known members of the genus Homo, had evolved by 2.5 million years ago. ...
6. Homo erectus, the PRESUMED ancestor of modern human populations evolved by 2 million years ago. H. erectus populations radiated out of Africa, into Asia and Europe. The oldest known fossils of early modern humans (H. sapiens) are from Africa; they are 100,000 years old. About 40,000 years ago, cultural evolution outstripped biological evolution of the human form.
7. Modern humans are adapted to a wide range of environments. This capacity resulted from evolutionary modifications in certain primate lineages. ...
p784 CONTROL OF HUMAN FERTILITY ...
... Each year in the United States alone, there are 1 million teenage pregnancies ...
... each year, there are 1.6 million abortions among all age groups.
... The motivation to engage in sex has been evolving for more than 500 million years. A few centuries of moral and ecological arguments for its suppression have not stopped all that many unwanted pregnancies. Besides this, complex social factors have contributed to a population growth rate that is out of control. ...
p806 ... If the annual current average rate of 1.55 percent (rates of increase for populations in the world) is maintained, the human population may be 10 billion to 11 billion by the year 2050. ...
... Today there is growing realization that population growth, resource depletion, pollution, and the quality of life are interconnected. ... most governments are trying to lower birth rates, as through family planning programs ... all offer information on the available methods of fertility control ...
p807 ... Family planning programs on a global scale are designed to help stabilize the size of the human population.
p809 ... We have arrived at a major turning point, not only in our biological evolution but in our cultural evolution as well. The decisions awaiting us are among the most difficult we will ever have to make, yet it is clear that they must be made, and soon. ... All species face limits to growth ... No amount of cultural intervention can hold back the ultimate check of limited resources and a damaged environment.
p883 HUMAN IMPACT ON THE BIOSPHERE Key Concepts:
... 5. Ultimately, the world of life depends
on energy inputs from the sun. That energy drives the complex interactions
among the atmosphere, ocean, and land.
Our
activities are disrupting the interactions in ways that may have severe
consequences in the near future.
6. We as a species must come to terms with principles of energy flow and principles of resource utilization that govern all systems of life on Earth.
pg901 Chap. 51 AN EVOLUTIONARY VIEW OF BEHAVIOR Key Concepts:
... 5. Like other traits having a genetic basis, behavior has evolved by way of natural selection. ... sexual selection and other evolutionary processes have favored behavioral mechanisms that enhance the ability of individuals to pass on their genes to offspring.
... 6. Evolved modes of communication underlie social behavior ...
p917 ... Evolutionary hypotheses about the adaptive value of behavior lend themselves to testing. And through such testing, we can gain understanding about the evolution of human behavior.